An Electromagnetic Pulse (EMP) is a short and intense burst of electromagnetic energy that can cause temporary or permanent damage to electrical equipment. A very large EMP could destroy the power and communications networks across continents. This could surprisingly easily lead to the collapse of modern society.
Causes Of A Large EMP
The two potential causes of EMPs large enough to cause widespread damage or destroy the power grid are weapons and solar storms.
EMP Triggered By Weapons
Gamma radiation produced by a nuclear explosion collides with air molecules, and this causes a massive electric field. Asymmetries in the electric field caused by air movement and earth’s surface generate the EMP. An EMP caused by a nuclear explosion at or near ground level will be very small. A nuclear explosion at high altitude however will cause a massive EMP. For example, a ten megaton nuclear weapon detonated at an altitude of 200 miles above the centre of Europe would cause an EMP covering most of Europe.
EMPs can also be produced by non-nuclear weapons. Non-Nuclear EMP weapons, or E-bombs, produce an EMP capable of destroying electrical and electronic equipment. An E-bomb produces a much smaller EMP than a nuclear weapon of a similar size.
EMP Triggered By The Sun
A Coronal Mass Ejection (CME) is a burst of plasma ejected from the sun. A large magnetic field accompanies the burst of plasma. CMEs can travel huge distances in space, and frequently reach earth. When a CME collides with earth’s magnetosphere, it causes aurora and geomagnetic storms. If the magnetic field is powerful enough, it can cause widespread damage to electrical equipment. The largest of these known to hit earth so far was the Carrington Event in 1859, where the relatively new telegraph network was knocked out.
What About Smaller EMPs?
In this article, we’re generally looking at the effect of a large EMP. There are, however, smaller EMPs that occur more frequently. Small EMPs can still cause damage, but the effect is more localised. A flash of lightning, for example, can induce large currents in any nearby wires, including power transmission wires. The current surge can cause damage to any sensitive electronic equipment, such as computers that are connected to the power supply. Surge protectors offer some protection against EMPs caused by lightning strikes.
How Does An EMP Cause Damage?
The EMP induces large currents in wires that are in its path. The same effect can be seen when a wire is moved through a magnetic field.
The wires could be large power transmission lines all the way down to the tiny wires on printed circuit boards. The induced currents may be much larger than the wire, or anything connected to the wire, is designed to handle. The huge induced currents simply fry the wires and connected equipment.
The end result of a huge EMP would be massive destruction of the power grid, communication network, and electrical or electronic equipment.
How To Protect Electronics Against An EMP
A Faraday shield or Faraday cage are enclosures designed to block the contents from an electromagnetic field. A Faraday shield is fully enclosed with conductive material, whereas a Faraday cage is a mesh of conductive material. The term Faraday cage is often used to refer to a Faraday shield too. Electrical equipment inside a Faraday cage has some protection from the effects of an EMP.
How To Survive An EMP That Brings Down The Power Grid
There are differing opinions in the scientific community about whether a huge EMP could totally wipe out the power grid or not. Some sources believe that an EMP might only cause damage at a localised level, which could be repaired within weeks. Others believe that the damage could destroy infrastructure across continents.
We like to be prepared for the worst, so let’s look at what would happen if an EMP totally destroyed the power grid.
What Will Happen When The Grid Goes Down?
The immediate effects of the EMP causing the grid to go down will be obvious. There will be no electrical power supply, and any electrical equipment or devices may not work at all. Shops and banks rely on electricity for processing transactions. Shops will close, or may allow cash sales. Banks will close, and cash machines will not be working. Nobody will be able to withdraw cash from their bank accounts.
The majority of our water supply uses power for pumping and water processing. Within a few hours of the grid going down, the water supply will also fail. There will be no mains water supply for drinking, hygiene or flushing toilets.
The transportation network will be next to fail. Any shops that have managed to stay open will rapidly run out of supplies. Even if the transport network was still working, without power the food production industry will grind to a halt anyway.
As people realise that food and water are running out, panic will set in. Social unrest will follow quickly, with looting and violence as people try to find food and water.
Over the coming weeks, the lack of food will lead to mass starvation. Hygiene and sanitation problems will lead to disease. Between them, starvation and disease will kill many.
Check out our Grid Down article, in which we take a much more in depth look at what happens in the hours, days and weeks after the grid goes down.
How To Survive An EMP
Surviving the EMP itself is simple. EMPs don’t directly cause any harm to people. What you need to survive is the massive grid down scenario that could follow. Prepare for this by making sure that you have everything that you need to live long term with no power. Our Grid Down article covers everything that you need to be able to survive when the power grid fails.